Metal tempering apparatus



My 13 1952 R. J. LINNEY 2,596,493

METAL TMPERING APPARATUS Filed April 28, 194s 2 SHEETS-SHEET 1 Vil AofeA/EYS May 13, 1952 Filed April 28, 1948 R. J. LINNEY METAL TEMPERING APPARATUS 2 SHEETS-SHEET 2 A rrojewys Patented May 13, 1952 UNITED STATES PATENT OFFICE METAL TEMPERING APPARATUS Robert J. Linney, Port Henry, N. Y.

Application April 28, 1948, Serial N o. 23,693

7 Claims.

This invention relates generally to the art of metal heat treatment, and particularly to a new apparatus for the tempering of ferrous metal objects, especially drill bits.

In the manufacture of certain metal articles it is quite important that they should be properly tempered, that is, so cooled from a heat-treating temperature that they will possess the desired properties. For example, steel bits used with drilling machines for drilling holes in hard rock should be properly and uniformly tempered. Frequently a plurality of bits of progressively decreasing size are used in drilling a single hole, the largest drill being used irst and the smaller ones following thereafter in the decreasing order of their sizes. If one of the bits should be improperly tempered, for example, if it should be softer than the succeeding bits, it will not make a hole of the desired size for succeeding bits and may stick in the hole. Hence, it is important that each bit of a set of drill bits should be properly and uniformly tempered, but it is also important that all bits whether intended for use in a certain set or not should be properly and uniformly tempered.

So far as I know, it was not possible, prior to the present invention, automatically `totemper steel drill bits properly and uniformly or to insure that the tempering` will be proper and uniform from bit to bit. By the present invention I am able not only to temper steel drill bits and also other metal objects properly, but also to insure that all the objects of the same composition will be tempered properly and substantially uniformly.

The present invention is predicated on the discovery that proper and uniform tempering may be attained by cooling highly heated metal objects with a predetermined amount of cooling liquid maintained at substantially constant temperature, or by exposing `the highlyheated ob jects to the cooling effect o f a substantially uniform temperature coolant for a predetermined length of time, then transferring the thus partially cooled objects, without substantial decrease in their temperature, to a second cooling liquid maintained at a lower temperature and allowing the objects to cool to, the temperature of that liquid.

In the drawings accompanying and forming a part of this specification,

Fig. 1 is a top plan view of one form of apparatus embodying the present apparatus in vention and with which the present method invention may be practiced;.

Fig. 2 is an elevational view taken from the chute side of the apparatus of Fig. 1; and

Fig. 3 is an elevational view taken from the left side of Fig. 1,.

In the drawings the reservoir I is provided with a drain pipe 2 controlled by a valve 3 and an overflow pipe ll. Liquid is maintained in reservoir I to the level indicated by line 5. Liquid may be brought into` reservoir I through pipe 6 which is equipped with a thermostatically controlled valve 'I. In this case the thermostat 8 is of the electrical type and is connected through lead 9, panel IU and lead II to an electrical device I2. 'I'he thermostat 8 and the device I2 may be, respectively, the well-known Mercoid thermostat control and Mercoil magnetic valve. When the temperature of the liquid in reservoir I rises above a predetermined point the thermostat 8 actuates the valve I2 and opens valve 1, thereby admitting cold liquid through pipe 6. Since the discharge end of pipe 6 is remote from the thermostat 8, the incoming fluid will continue to ow for some little time before the thermostat 8 will be actuated by a lowering of the temperature of the liquid in reservoir I to de-energize the Valve control device and close the valve 'I against further entry of cold liquid.

Adjacent to the thermostat 8 is disposed a pump I3 which communicates with the interior of the reservoir I and serves to withdraw liquid therefrom and to force it through pipe I4 and into the top of a hollow shaft presently to be described. The pump I3 is actuated by a motor I5.

Two upright beams I5 are disposed on opposite sides of reservoir I and are connected together at their upper ends by a channel I7 and at a point some little distance above the top of reservoir I by a pair of channels I8. An upright leg or beam I9 also located outside of reservoir I is connected at its upper end to one or more channels 20 which extend horizontally to- Ward and connect to one of the channels I 8. A plate or platform 2| rests on channels 210 and is secured to channels I8 and 20 and serves as a support for a power unit consisting of a motor 23 and a reduction gearing device 23. Panel I0, above mentioned, is secured to channel Il, to one of the uprights I6 and to plate 2|.

The plate 2I supports a thrust bearing 25 which, in turn rotatably supports the hollow shaft 2G above mentioned. This shaft passes through a pillow block orbearing 21 on channel I'I. A sprocket 28 is keyed to shaft 26 and is connectedV to the reduction gearing device 23 by I3, is connected with the upper end of hollow shaft 26 by a packing nut.

The hollow shaft 26, at its lower end, is connected to a tank 30 into which liquid may ow from shaft 26. Tank 30 is provided with a plurality of members 3| which may be called fountains or spray-heads, each comprising a right angled pipe 32 communicating with the interior of tank 30, and an enlarged upper Vend 33- provided with a screen on which an object to be tempered may be placed. it will be understood that when pump I3 withdraws liquid from tank I and forces it through pipe Ie into hollow shaft 2G, such liquid will ll the tank and will ow out through pipes 32 and up through theperiorations in the screen and against an object on the screen. It will also be understood that when the motor 22 is actuated the chain 29 will rotate shaft 26, tank 30 and members 3l and that by varying the'speed of rotation of the shaft objects on those members may be'subjectedforvarious lengths of time to cooling liquid nowing thereagainst through said members.

Y A magnet 40 is mounted on supports 4I which are connected to reservoir I by arms d2. This `magnet is adjustably positioned relative to metallic articles Von the Vrspray-heads, so that when energizedV the magnet may attract to itself and thereby remove from an adjacent spray-head a magnetic metal article on the'latter. The magnet '40 is alternately'energized for a'short period of time and then isV cle-energized for another short period of time. The top of tank'i is provided with a'plurality of pegs dp'ositioned radially inward of the respective spray-'heads' 3i. These pegs 45 are so disposed as to make contact with the switch closingA 'member iii of a Alimit switch 41 `which is connected to a suitable source of electric current and also to the windings of 'magnet 40. When 'one of these pegs 45 closesthe contacts of the limit switch 41 the Velectrica-lv current energizes magnet 40 and the magnet in turn attracts to itself a metal object onithe spray-head adjacent the magnet. When the peg 45 moves on and permits the contacts of the limit switch d1 to separate, the current to -ma-gnet 4I)Y isinterrupted and the metal object which had been attracted to the magnet is allowed to fall. In this way the magnet is energized for alshorttime and then is de-energized for another short time, and the energization occurs when a spray-head is adjacent to the magnet.

- lAn..inclined chute 5011s disposed with its upper endinposition to 'receive metal articles -which fall from-the de-energized magnet 40. The lower Aof a heating unit 53 which may be of any suit- Yable construction, lfor example, the well-known Calrod immersion heating unit.

The general operation ofY the above described apparatus'will be understood from the foregoingde'scription. However, when it is to be operated to temper steel drill bits for hard rock drilling it "may be operated substantially as follows: VThe motor I is venergizedand"pump I3 cireulates coolant from-reservoir I throughnipe l brings the level of coolant in tank 30 to above the tops of heads 3l so that the coolant will overnow the heads and return to reservoir I. The motor 22 is energized and tank 30 is rotated, Then steel drill bits which have been heatedY to the proper temperature, which may be about 1440" F. for one particular kind of steel,rare removed from the heating furnace and are placed one at a time points down'on the spray-heads when they reach the position indicated by the letter X in Fig. l and while tank 30 is rotating.

v As tank 30 rotates, the pressure exerted on the cooling liquid is so regulated that the liquid bubblesup through the spray-heads and to a predetermined distance thereabove which is suicient to cover 'only the drilling points of the bits or about fg" for the average size jack bit. This liquid is maintained at a temperature under 75 F. preferably at about 72 F. The liquid thus regulated as to pressure and temperature cools the points from/'the time they leave point X-until they reachthe position-indicated bythe letter Y in Fig. l.' 1 When a bit reaches"that position, a peg 45 several stations behind that spray-head will close the Vcircuit'through limit switch 41, thereby energizing magnet-"40. K4When venergized this magnetattracts to itself the drill bit on the spray-head at station Y and whendeenergized drops'that Ydrill bit onto chute 50 and the bit slides into tank 5I. k y

It-will' lne-understood that during'the time of about 53 seconds which elapses between the -placing of a bit on Va spray-head "at station X land theitime the drill bit is removed therefrom' at -statio'n Y, the liquid coming into contact 'with the drill bit will have lowered thev temperature of the drillbitconsiderably, for example, from about- 144:0o F. to about 900 F., that' the bit will then be at a temperaturefwithin `the magnetic temperature range ofv the steel,` :and that the temperature of the drill bit willfnot' sensibly decrease between the time it is removed at station Y and the time it arrives intank 5I. The speed of rotation of tank should'be so"adjusted for bits of different sizes thatthe' bits are cooled through the just mentioned range during one revolutionV of the tank. Higher or lower'speeds may, of course, be' used when smaller or greater decreases in temperatures are desired.

lDrill bits vof the type referred'to herein'a're composed of steel which can be made quite yhard by heat treatment. While drill' bits are made from steels of different S. A', `li!."nurnbers,`V the compositions which are suitable contain between about .70%and .90% of carbon,`betweenabout .40% and` .60% of'rnan'ganese, about .03% maximum of sulfurand of phosphorous, with the remainder being iron containing small amounts of other impurities but without any substantial amounts of alloying elements. The cutting-edges are voften formed on these bits when the carbides in the steel are in a spherodized condition and the steel is soft and machinable yasa result thereof. Then the steel is heated tosuch a -temperature'as will result in a complete solution ofthe carbides which in this 'caseis about-1440 F. VThen the dissolved carbides inthecutting edge portions Vare precipitated as very fine grain martensite more or less uniformly throughout those portionsl by quenching the Acutting edges of the bit with resultant hardening of those portions. This quenching step is .carried out by quickly lowering the temperature of the cutting edgeportions "from about 14.4.0212 .t'oY about 1.900n l1i. in a short space of time` a'sbybubblingw'ater beyond the cutting at about 72 F. to 75 F. over the cuttingsurfaces for about 51 seconds on the average. `The entire bit is cooled by the extraction of heat from the body of the bit through the surfaces in contact with the water but the cooling rate of the metal edge portions is less rapid and hence the body part of the bit is more ductile and resistant to breakage than the cutting edges. The thus quickly cooled article is transferred, preferably magnetically, when at a temperature of about 900J F. into a body of water maintained, for example, at about 192 F. where it is allowed to cool for about l minutes. If desired, the bit may be reheated to a drawing temperature to reduce the .brittleness of the cutting edge portions.

Since the cooling rate of the drill bits in tank should not be too rapid, the temperature of the liquid is maintained above a predetermined minimum temperature by the heating unit 53.

Various cooling liquids may beused in reservoir and stationary tank 5| as desired. Water may be used in reservoir I but its temperature should not be permitted to rise beyond a certain point for if it becomes too highly heated, due to heat extracted from the bits, it willnot cool `the bits below their non-magnetic range and hence the magnet 40 will not attract them to it. When the liquid in reservoir is maintained at a temperature not in excess of about 75 F. and the speed of rotation of tank 30 and the rate of liquid now through the spray-heads are properly adjusted, tool bits having a temperature of about 1440 F. when placed on the spray-heads will be cooled to below their non-magnetic temperature range before they reach the magnet 40 and hence will be attracted to the magnet and removed from the spray-heads. By suitably setting the thermostat 8 the temperature of the coolant in reservoir may be maintained substantially constant, as above mentioned.

The coolant preferred in tank 5| is water and its temperature is preferably maintained close to its boiling point by the heating unit in the bottom of the tank, 192 F. having been found to be satisfactory.

Each bit cools to about the temperature of the water in tank 5| within about 10 minutes and may then be removed for subsequent treatment.

While the foregoing detailed description is specic to the tempering of drill bits, it will be understood that apparatus embodying the present invention may be used for tempering other articles, and that by adjusting the speed of rotation of tank 30 and the temperature of the coolant in reservoir and the rate or amount of coolant flow through spray-head 3|, various metal objects may be cooled throughout various temperature ranges and to various temperatures, depending on the characteristics desired in the objects and obtainable by such variations in the time, rate and nature of the tempering action. It will also be understood that by varying the kind and temperatureof the coolant in tank 5|, the rate of cooling of metal articles therein may be varied with some variation in the properties of the articles cooled under those conditions.

This application is a continuation-in-part of my application Serial No. 499,398, filed August 20, 1943, and abandoned on or about May 5, 1948. Subject matter disclosed but not claimed herein is being claimed in my co-pending application Serial INo. 252,629, filed October 23, 1951, which is a division of this application.

Having thus described the present invention so that others skilled inthe art may be able to understand and practice the same, I state Vthat what I desire to secure by Letters Patent is dened in what is claimed.` i

What is claimed is:

1. Apparatus for tempering metal objects comprising a rotatable tank having a plurality of spray-heads adapted to carry heated metal objects to be tempered, means to deliver cooling liquid through said spray-heads and against such objects on the latter, means including a thermoon the latter, means including a thermostat controlled liquid inlet for maintaining liquid in the reservoir below a predetermined temperature, and means for removing thus cooled objects from said spray-heads, said means including a magnet in fixed position above and outside of the line of travel of said spray heads.

3. Apparatus for tempering metal objects comprising a reservoir for liquid, a rotatable tank having a plurality of spray-heads adapted to carry heated metal objects to be tempered, means to circulate liquid from the reservoir to the tank and spray-heads and against such objects on the latter, means including a thermostat controlled liquid inlet for maintaining liquid in the reservoir below a predetermined temperature, a stationary tank for cooling liquid, and means for transferring thus cooled objects from said. sprayheads into liquid in said stationary tank, said means including a magnet in xed position above and outside of the line of travel of said sprayheads and a chute inclined downwardly from below said magnet to above said stationary tank.

4. Apparatus for tempering metal objects comprising a reservoir for liquid, a rotatable tank having a plurality of spray-heads adapted to carry heated metal objects to be tempered, means to circulate liquid from the reservoir to the tank and spray-heads and against such objects on the latter, means including a thermostat controlled cold liquid inlet for maintaining liquid in the reservoir below a predetermined temperature, a stationary tank for liquid, means to maintain substantially constant the temperature of liquid therein, and means including a magnet for transferring thus cooled objects from said spray heads into liquid in said stationary tank.

5. Apparatus for tempering metal objects comprising a rotatable tank containing cooling liquid and having a plurality of members adapted to carry heated ferrous metal objects to be tempered, means to deliver liquid from said. tank against such objects on said members to cool them to below the upper limit of their magnetic temperature range, and means for transferring the thus cooled objects from said members, said means including a magnet in fixed position above and outside of the line of travel of said members and means to energize and de-energize said magnet when one of said members is moving therepast.

6. Apparatus for tempering metal objects comlof spray-heads adaptedl prising a rotatable tankicontainingcoioling liquid vand having a plurality ofmem'bers-adapted .to carry heated rferrous vmetalxobjects to be, tempered, means to 'deliver liquid-'from said tank against said objects on fsaid membersY to vcool them to below the upperlimitiof their magnetic Vtemperaturev range, ltemperature control -means to maintain substantially constant the temperaing a magnet in"xed positionabove andgoutside ofthe line of: travel ofvsaidmembersf-and means to energizet'andide-energize said 4magnet when one ofA said. members is :movedftherepast- 7. rApparatus for tempering metalrobjects comprising a reservoir for liquid, a: rotatable tank within said reservoir and having a plurality `to carry Vheated :metal objects to be temperedmeans1torotateqsaid tank, means to circulate-'liquidfrom .the reservoir through the tank: .and spray-lfleads;V and gagainst such objects-'on the latter, means including a thermostat controlled `cold liquid 'inletor maintaining liquid in theh reservoir belowa predetermined'temperature, a liquid containing-stationaryV tank, means to :maintainsubstantially .constant the temperature of liquid therein, and means for transferring cooled objectsfrom said spray-heads to said stationary tank^said means including. a :magnet adjacent `to the "path of travelfofobjectsonf-sad sprayrheads, aglimit -:switch .connectedto :the .fof electrical currenn'abutments connected to `said revolving tank to `close said switch, and

magnet and to a source apchute positioned toreceive the metal objects released from the magnet when it is `nie-energized .andtoconduct theminto said rstationary tank.

s ROBERT J. LINNEY.

.REFERENCES CITED vThe following references are. of record inthe -file of this patent:

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